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Orient a Map Using a Lensatic Compass
071-329-1011


Conditions: Given a field table, a standard 1:50,000 scale military map, a protector, a pencil, paper, and a compass in daylight.

Standards: Orient the map to the ground using a compass. The North-seeking arrow of the compass must fall within 3 degrees (50 mils) of the angle shown in the
grid-magnetic (G-M) angle on the map's declination diagram.

Performance Steps
1.        With the map level, place the compass parallel to a North-South grid line with the cover side of the compass pointing towards the top of the map. This will place
the black index line on the dial of the compass parallel to grid north. Since the needle on the compass points to magnetic north, a declination diagram on the face of
the compass is formed by the index line and the compass needle.
2.        Rotate map and compass until the directions of the declination diagram formed by the black index line and the compass needle match the direction shown in
the declination diagram printed on the margin of the map. Orient the map.
NOTE: If the magnetic north arrow on the map is to the left of the grid north, the compass reading equals the G-M angle (given the declination diagram). If the magnetic
north is the right of the grid north, the compass reading equals 360 degrees (6400 mils) minus the G-M angle.
3.        Remember to point the compass north arrow in the same direction as the magnetic north arrow (2 above). The compass reading (equal to the G-M angle or the
360 degrees [6400 mils] minus the G-M angle) will be apparent.
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NOTE: If the G-M angle is less then 3 degrees (50 mils), do not line up the north arrow.
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4.        Some maps have a built-in protractor considering of a pivot point "P" on the south neat line of the map and several degrees of arc along the north neat line of the
map. Obtain the G-M line by connecting pivot "P" with the appropriate value of the G-M angle (taken from the declination diagram) on the arc. Place the compass
parallel on this line. Rotate the map and compass until the needle point aligns with the continuous line formed by the index line and the sighting wire. Orient the map.
5.        An alternate method is to draw a magnetic north line on the map from any N-S and E-W grid line intersection using the protractor.
a.        Align the straightedge of the compass along this magnetic north line.
b.        Rotate the map and compass together, until the north arrow falls beneath the fixed black index line on the compass.

Evaluation Preparation: SETUP: Select an area that is free of magnetic interference (vehicles). Provide a field table, 1:50,000 scale military map, a protractor, a pencil,
paper and compass.

BRIEF SOLDIER: Tell the Soldier to orient the map to the ground using the compass. Tell the Soldier to use the G-M angle shown by the declination diagram if it
exceeds 3 degrees (50 mils).

                                                                                                                                                                                                            Performance Measures        GO        NO-GO
1.        Determined whether G-M angle exceeded 3 degrees (50 mils).                                                                                                                                       ——        ——
2.        Aligned the side of the compass with one of the north-south grid lines.                                                                                                                          ——        ——
3.        Positioned the cover of the compass toward the top of the map.                                                                                                                                       ——        ——
4.        Oriented the map.                                                                                                                                                                                                                         ——        ——
5.        Corrected the orientations of the map when the G-M angle exceeded 3 degrees (50 mils) using one of the following methods:                       ——        ——
a.        Formed the G-M angle with the black index line and the needle on the compass.                
b.        Used the pivot point "P" on the south neat line and the degrees of arc along the north neat line; placed the compass along this line.                
c.        Drew a magnetic north line from any N-S and E-W grid line intersection using a protractor and placed the compass along this line.                
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NOTE: Steps 5 were only required when the G-M angle was greater than 3 degrees or 50 mils. Step 5b was only tested if the map had the built-in protractor.
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Evaluation Guidance: Score the Soldier GO if all performance measures are passed. Score the Soldier NO-GO if any performance measure is failed. If the Soldier
scores NO-GO, show the Soldier what was done wrong and how to do it correctly.

References
Required        Related
FM 3-25.26  
 
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